Method for constructing structure

ABSTRACT

The present invention relates to a method for constructing a structure, the method comprising constructing an underground structure on the ground, and then constructing the structure in the ground by sinking same into the ground.

TECHNICAL FIELD

The present disclosure relates to a method for constructing a structure,and more particularly, to a method for constructing an undergroundstructure above ground and sinking the same into the ground, rather thaninstalling the same underground.

BACKGROUND ART

In constructing a basement floor on a ground with a high level ofgroundwater or soft ground, the outflow of groundwater may cause seriousdamage to not only underground structures such as adjacent tunnels, boxstructures, and subways, but also ground structures.

When excavation is performed beyond a certain depth, the safety ofadjacent structures is partially checked before construction through theexcavation depth or the like. However, in actual construction, evenlife-threatening accidents frequently occur due to the collapse of theearthen barrier or the like. In addition, adjacent structures or roadsundergo cracks, differential settlement, and sinkholes.

In recent years, even at excavation sites where the excavation depth isnot relatively deep, which is not the target excavation depth, thecollapse of an adjacent building has occurred due to the collapse ofearthen barriers or the outflow of groundwater. As such, excavation forthe construction of underground structures in urban areas is a verydifficult task. Therefore, there is a need for a method for excavationand structure construction for safer and more stable construction ofunderground structures.

FIG. 1 shows an underground structure that is generally used andconstructed after excavation. As shown in FIG. 1, the conventionalconstruction method is to construct an underground structure afterexcavating underground soil. That is, an earthen wall 500 is installedadjacent to the land boundary line, and a center pile 700 is installedin the excavation area. Then, excavation and installation of a strut 600are repeated to complete the underground excavation. While constructingthe foundation, retaining wall and basement floor, the strut 600 and thecenter pile 700 are removed to complete the underground structure.

There are various excavation methods. Various methods for earthenbarrier construction are also applied depending on the conditions of theground, and various water cut-off methods are applied depending on thelocation of the groundwater level. After the excavation is completed,the underground structure is constructed. Alternatively, a top-downmethod in which the structure is constructed from the top to the bottomwhile constructing the temporary earthen barrier structure is used.

The conventional underground structure construction method forconstructing a structure after excavation raises the following issues interms of safety and economic feasibility. In terms of safety, damage iscaused to surrounding facilities due to excavation and loss of life iscaused by the collapse of the earthen barrier structure. In terms ofeconomic feasibility, the land is not sufficiently used and constructioncosts are wasted due to the construction of earthen barriers.

In other words, due to the earthen wall, the underground structure isonly constructed at a certain distance from the land boundary line, andaccordingly a considerable underground area cannot be used. As a result,economic losses are great.

Korean Patent Application Publication No. 10-2013-0061368 relates to anunderground structure construction method for constructing anunderground structure such as a basement floor of a building or asubway, or burying an underground pipe, but fails to address theabove-mentioned issues.

Therefore, there is a need for development of a safe, economical, andfast structure construction method.

DISCLOSURE Technical Problem

Therefore, the present disclosure has been made in view of the aboveproblems, and it is one object of the present disclosure to provide anefficient structure construction method capable of ensuring safetyaround a construction site, reducing construction costs, and shorteningconstruction time.

Technical Solution

In the present disclosure, a structure construction method forconstructing an underground structure on the ground and sinking the sameinto the ground includes steps of: A) constructing a foundation plate 10and a pile 20; B) installing a jack-down device and constructing abasement structure; C) performing excavation under the foundation plate10 and sinking the underground structure; and D) dismantling thejack-down device and fixing the pile 20, wherein the jack-down device isinstalled on the foundation plate 10, such that a degree of sinking ofthe underground structure is controlled by adjusting force of thejack-down device, wherein the excavation under the foundation plate 10and the sinking of the underground structure are performed in parallel.

In the present disclosure, a structure construction method forconstructing an underground structure on the ground and sinking the sameinto the ground includes steps of: a constructing an outer foundationplate 50 and a pile 20; b) installing a jack-down device; c) performingexcavation under the outer foundation plate 50 and sinking theunderground structure; and d) dismantling the jack-down device andfixing the pile 20, wherein the jack-down device is installed on theouter foundation plate 50, such that a degree of sinking of theunderground structure is controlled by adjusting force of the jack-downdevice, wherein the excavation under the outer foundation plate 50 andthe sinking of the underground structure are performed in parallel.

The sinking is performed by a weight of the underground structure.

Alternatively, the sinking is performed by a weight of the undergroundstructure and additional external force.

The additional external force is generated by: increasing the load byadding a temporary load to the underground structure; using a rockanchor or earth anchor installed in the ground; or using main surfacefriction of the pile installed in the ground.

The excavation is performed by: using excavation equipment; using awater jet; or suctioning and discharging soil from the ground.

The method further includes constructing an additional foundation plateon the foundation plate 10 and the pile 20 after the step D).

The method further includes constructing an additional foundation plateon the outer foundation plate 50 and the pile 20 after the step d).

Advantageous Effects

The structure construction method according to the present disclosurehas the following effects.

First, an excavation wall and an outer wall, which are the structures ofan underground structure, may function as a structure, while being usedas earthen barriers during the construction process. Accordingly, soilleakage and water may be prevented in the vicinity of new construction,and thus the safety of nearby facilities may be secured.

Second, when the conventional method is used, groundwater leaking duringexcavation is discharged through pumping, which lowers the surroundinggroundwater level, thereby producing a sinkhole and causing a safetyrelated problem to adjacent structures. On the other hand, according tothe present disclosure, the groundwater is not discharged out, butexcavation is performed using a water jet in some cases. Accordingly,decrease in the surrounding groundwater level, which causes problems,may be prevented.

Third, according to the present disclosure, there is no need for a watercut-off method including a temporary earthen barrier facility, and thereis no risk of collapse in excavation. Therefore, instability of thetemporary structure raising several issues may be prevented.

Fourth, since temporary earthen barrier facilities are not required,time and costs required for installing and dismantling the temporaryearthen barrier facilities may be reduced, shortening the constructionperiod and reducing construction costs.

Fifth, since the surrounding ground is firmly supported by theexcavation wall and the outer wall before excavating the ground,disturbance of the surrounding ground may not occur.

Sixth, as the earth wall is not installed, the underground structure maybe constructed up to the land boundary line. Accordingly, the utilityvalue of the land may be increased and the underground space may be usedas much as possible.

Seventh, the pile for construction of an underground structure mayfunction as a support and guide to control settlement of the undergroundstructure during construction, and function as a deep foundation afterconstruction is completed.

Eighth, the amount of settlement of underground structures may becontrolled using a hydraulic jack. Accordingly, precise construction maybe ensured.

Ninth, since the temporary earthen barrier facility is not required,accidents caused by the collapse of the temporary earthen barrierfacility may be prevented.

DESCRIPTION OF DRAWINGS

FIG. 1 shows conventional technology.

FIGS. 2 to 7 illustrate a procedure according to a first embodiment ofthe present disclosure.

FIGS. 8 and 9 illustrate a second embodiment of the present disclosure.

FIGS. 10 and 11 illustrate a third embodiment of the present disclosure.

FIG. 12 is an enlarged view of a foundation plate, a pile, and ahydraulic jack.

BRIEF DESCRIPTION OF REFERENCE NUMERALS

-   -   100: Underground structure    -   10: Base plate 11: Block out    -   12: Excavation wall 13: Tip shoe    -   14: Equipment entrance 20: Pile    -   30: Second basement structure    -   31: Bottom plate 32 Outer wall    -   33: Pillar 34: Second basement floor    -   40: First basement level structure    -   41: Bottom plate 42: Outer wall    -   43: Pillar 44: First basement level    -   50: Outer foundation plate    -   60: Outer basement structure    -   300: Hydraulic jack    -   310: Anchor 311: Anchor fixture    -   320: Pressure plate 330: Pressurizing stand    -   400: Land boundary line    -   500: Earth wall 600: Strut    -   700: Center file

BEST MODE

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings such that those ofordinary skill in the art can easily implement the present disclosure.However, the present disclosure may be implemented in various differentforms and is not limited to the embodiments described herein. In thedrawings, parts irrelevant to the description are omitted in order toclearly describe the present disclosure. Similar reference numerals areused to refer to similar parts throughout the specification. Throughoutthe specification, when a certain portion “includes” or “comprises” acertain component, this indicates that other components are not excludedand may be further included unless otherwise noted. Hereinafter,preferred embodiments of the present disclosure will be described indetail with reference to the accompanying drawings.

Conventionally, an underground structure is constructed in anunderground space after excavating the ground. On the other hand, in thepresent disclosure, a structure is constructed in a manner in which anunderground structure is constructed on the ground, and then sunken intothe ground while excavating the part under the foundation plate.

The underground structure 100 of the present disclosure includes afoundation plate 10, a pile 20, and a basement structure. The basementstructure may have one layer or two or more layers. In first and secondembodiments, the basement structure includes a 2-level basementstructure 30 and a 1-level basement structure 40.

FIGS. 2 to 7 show the first embodiment of the present disclosure forconstructing the underground structure 100. Hereinafter, eachconstruction step in the case of constructing the second basement floorwill be described in detail with reference to FIGS. 2 to 7.

{circle around (1)} Construction of the Foundation Plate 10 (See FIG.2).

A foundation plate 10 made of reinforced concrete is constructed on theground. As shown in FIG. 2, the edge of the foundation plate 10 may bedirectly adjacent to the land boundary line 400, or may substantiallycoincide with the land boundary line 400.

In the construction method, the outer wall of the underground structureis used as an earthen barrier. Accordingly, a separate earthen barrieris not required. The foundation plate and the outer wall of theunderground structure are constructed so as to contact the land boundaryline as much as possible to maximize the underground space.

First, since the foundation plate 10 is constructed, and then the pile20 is constructed, a hole through which the pile 20 can be installedshould be formed in the foundation plate. Therefore, in constructing thefoundation plate, a sleeve for forming a hole for the pile 20 isinstalled in advance. A steel pipe may be used as the sleeve.

After sinking of the underground structure is completed, a groove isformed in the foundation plate by a certain thickness to form a blockout11 in order to make a space for fixing the upper part of the pile 20 tothe foundation plate (see FIG. 12). After fixing the file, grouting isperformed in the blockout 11.

An excavation wall 12 may be arranged at the lower edge of thefoundation plate 10. The excavation wall 12 may be used as an earthenbarrier wall during excavation work. In addition, a tip shoe 13 havingan inclined tip is disposed at the lower end of the excavation wall 12,such that the underground structure may be easily inserted into theground.

To form the tip shoe 13, a steel plate, which is a permanent mold, maybe used or concrete may be formed to have an inclined cross section.

After the excavation wall 12 is first constructed, concrete for thefoundation plate is poured such that the excavation wall 12 and thefoundation plate 10 are integrated.

In constructing the foundation plate 10, a required number of jack-downanchors 310 may be pre-installed by calculating the load of theunderground structure (see FIG. 12). The quantity and capacity of theanchors 310 may be applied according to the weight of the undergroundstructure and the load generated when the underground structure issunken.

The lower end of the anchor 310 is provided with an anchor fixing member311 for fixing the anchor to the foundation plate. The anchor fixingmember 311 may be buried in the foundation plate 10, or may be fixed tothe bottom of the foundation plate 10.

It has been described that the anchor 310 for jack-down ispre-installed. In some cases, however, the anchor may not bepre-installed. Instead, the jack-down may be performed after installinga chemical anchor after construction of the foundation plate.

The thickness of the foundation plate is determined in consideration ofthe load required for jack-down and the structural stability of theunderground structure.

{circle around (2)} Construction of the Pile 20 (See FIG. 2).

When the foundation plate 10 is installed, the pile 20 is installedthrough a hole formed by the sleeve for construction of the pile 20. Thepile 20 may be a steel pile, a ready-made reinforced concrete pile, aPHC pile, a composite pile, a cast-in-place concrete pile, or the like.Installation of piles may be performed using a method such as driving,drilling after excavation, or the like. The pile is installed up to thebasement bedrock that may exhibit the end bearing capacity.

When the pile 20 is not used as a deep foundation after construction ofthe underground structure is completed, that is, when the foundation isa spread foundation rather than a pile foundation, only minimumtemporary piles required for jack-down of the underground structure maybe constructed.

In the case of an underground structure designed with a pile foundation,the jack-down device may not be installed on every pile, but may beinstalled only on as many piles as necessary to jack down theunderground structure. The load to be applied at this time is applied inconsideration of the weight of the underground structure constructedduring jack-down and the amount of reduction due to buoyancy.

In the case of an underground structure designed with direct foundation,the minimum number of piles necessary for jack-down is constructed andused for jack-down. The load to be applied at this time is applied inconsideration of the weight of the underground structure constructedduring jack-down and the amount of reduction due to buoyancy.

{circle around (3)} Installation of Jack-Down Device and Construction ofBasement Two-Story Structure (30) (See FIG. 3)

A jack-down device capable of controlling the settlement amount andsettlement speed of the underground structure is installed, and thebasement two-story structure (30) is constructed. At this time, in orderto reduce the construction period by efficiently proceeding the work,construction of the second basement structure 30 may be performed whileinstalling the jack-down device.

Referring to FIG. 12, which shows a jack-down device, a pressurizingstand 330 is fixed to the top of the pile 20, and a hydraulic jack 300is installed on the pressurizing stand 330. The lower end of the anchor310 is fixed to the foundation plate 10 by an anchor fixing member 311,and the upper end of the anchor 310 is fastened to the pressure plate320. A nut may be used to fasten the upper end of the anchor 310 to thepressure plate 320. By controlling the pushing force that the hydraulicjack 300 applies to the pressure plate 320, the amount of settlement ofthe foundation plate may be precisely controlled.

The jack-down device shown in FIG. 12 is merely an embodiment, and thehydraulic jack, the anchor, the pressure plate, and the pressurizingstand may be combined in a different structure.

The second basement structure 30 may include a bottom plate 31, an outerwall 32, and a pillar 33. The outer wall 32 may function as an outerwall of the underground structure and an earthen barrier at the sametime. The pillar 33 includes a pillar and a wall supporting the bottomplate 31.

{circle around (4)} Excavation Under the Foundation Plate 10 andJack-Down of the Underground Structure (See FIGS. 3 and 4)

When the part under the foundation plate is excavated after theinstallation of the jack-down device is completed, the second basementstructure will naturally sink due to its own weight and the weight ofthe foundation plate.

Various methods may be used to excavate the part under the foundationplate depending on the condition of the ground under the plate.

In the case of soft ground, the soil under the foundation plate may beremoved by suctioning the soil. The jack-down device is to be controlledwhile accurately measuring the amount of settlement such that thestructure does not non-uniformly sink when the soil is removed. After acertain amount is excavated, the structure is sunken using the jack-downdevice. This process is repeated to place the underground structure at adesired location. Depending on the viscosity and moisture content of theclay, water jetting and agitation are performed to facilitate suction.The sucked muddy water is separated into soil and water through adewatering process. The separated soil and sand may be taken out to thesandy soil site and the separated water may be reused at the site toprevent environmental pollution.

When the ground under the foundation plate is relatively good, suctionor dewatering may be additionally performed together with water jettingor excavation may be performed in parallel to sink the structure.

When the ground under the foundation plate is hard like bedrock, anequipment entrance 14 is formed in the foundation plate, and the groundunder the foundation plate is excavated using the excavation equipment,and then the structure is brought down.

{circle around (5)} Construction of the First Basement Structure 40 (SeeFIG. 5)

When the second basement structure 30 is placed on the foundation plateand sinks by a required depth (FIG. 4), the first basement structure 40is constructed on the ground level on the second basement structure 30(FIG. 5).

The first basement structure 40 may include a bottom plate 41, an outerwall 42, and a pillar 43. The outer wall 42 also functions as an outerwall of the underground structure and an earthen barrier at the sametime. The pillar 43 includes a pillar and a wall supporting the bottomplate 41.

{circle around (6)} Repetition of Excavation Under the Foundation Plate10 and Jack-Down of the Underground Structure (See FIGS. 5 and 6)

After the construction of the first basement structure 40, theunderground structure is sunken by controlling the jack-down devicewhile excavating the earth under the foundation plate. The sinking isperformed up to the required depth (FIG. 6).

{circle around (7)} Completing Sinking, Dismantling the Jack-DownDevice, and Settling the Pile (See FIG. 7)

Once sinking to the required depth is complete, the jack-down device isdismantled. After cutting the anchor 310 and fixing the anchor 310 andthe upper end of the pile 20, grouting is performed in the blockout 11to fix the pile on the foundation plate.

After performing steps {circle around (1)} to {circle around (7)} above,the construction of the interior of the underground structure andconstruction of the ground structure are carried out as necessary. Then,the construction of the structure is completed.

FIGS. 8 and 9 illustrate construction of an underground structure 100according to a second embodiment of the present disclosure.

In the second embodiment, the pile 20 is first constructed, and then thefoundation plate 10 is constructed. In other words, in the secondembodiment, step {circle around (2)} is performed first, and then step{circle around (1)} is performed. Then, steps {circle around (3)} to{circle around (7)} are performed as described above.

In the first and second embodiments, the process of forming the firstbasement structure and the second basement structure has been described.However, the present disclosure is not limited to the first basementstructure and the second basement structure. That is, only the firstbasement structure may be formed, or a plurality of basement floors oftwo or more basement levels may be formed by repeating steps {circlearound (4)} and {circle around (5)} described above.

FIGS. 10 and 11 illustrate construction of an underground structure 100according to a third embodiment of the present disclosure.

The third embodiment may be applied when an area where an undergroundstructure is constructed is large. That is, when the plan area of theunderground structure is large, forming the entire foundation plate asone body and sinking the same may be difficult and have a risk ofdamaging the foundation plate, and may be rather inefficient.

In this case, an outer foundation plate 50 is constructed for a certainwidth at the land boundary line 400. Then, the outer foundation plate 50is sunken in the same manner as described above. An outer basementstructure 60 may be constructed on the outer foundation plate 50 andthen sunken. In this operation, while excavating the soil under theouter foundation plate 50, the outer foundation plate is sunken. Oncesinking of the outer foundation plate is completed, a foundation plateand the basement structure are constructed.

At this time, the internal soil inside the outer foundation plate 50 maybe left as it is. Then, the internal soil may be excavated after sinkingof the underground structure is completed. In addition, while the outerfoundation plate 50 is sunken by a certain degree, the internal soil maybe excavated.

In the third embodiment, after constructing the outer foundation plate50, the pile 20 may be installed. Alternatively, after installing thepile 20, the outer foundation plate 50 may be constructed.

In the above embodiments, it has been described that the foundationplate 10 or the outer foundation plate 50 is constructed as a singlefloor. In some cases, after the sinking is completed, an additionalfoundation plate may be formed on the foundation plate 10 or the outerfoundation plate 50.

That is, when a concrete pile or a pile with a large diameter is used asa pile foundation, it may be difficult to implement rebar arrangement onthe foundation plate 10 due to the pile. Further, it is difficult tofirmly fix the upper portion of the pile to the foundation plate.Therefore, after the sinking is completed, an additional foundationplate is preferably constructed on the foundation plate 10. Inconstructing the additional foundation plate, the jack-down foundationplate 10 is constructed as thin as possible. After the sinking of theunderground structure is completed, the pile and the foundation plate 10are settled. Then, rebar arrangement is performed on the pile and thefoundation plate 10, and then a mat (for the additional foundationplate) is poured to construct the additional foundation plate.

In constructing an additional foundation plate on the foundation plate10, the reinforcement and thickness of the entire foundation areconsidered and reflected in the floor height of the undergroundstructure. By constructing the additional foundation plate, sufficientrigidity of the mat may be obtained even with a pile having a largediameter. In addition, in constructing an additional foundation plate,reinforcing bars must be constructed in advance at a location determinedin consideration of the connection between the additional foundationplate and the foundation plate 10, and the connection between theadditional foundation plate and the wall and pillar.

On the other hand, when a steel pipe pile is used, an additionalfoundation plate may not be required, and only the foundation plate 10may be used because the diameter of the pile is not large enough tointerfere with the arrangement of reinforcing bars on the foundationplate.

In sinking an underground structure, it may be difficult to sink thestructure by the weight of the underground structure alone. In thiscase, the structure may be sunken using the following method.

First, a load may be added. The load may be increased by adding atemporary load on the foundation plate or the underground structure.

Second, a rock anchor or earth anchor may be installed in the ground,and the structure may be sunken by pulling the rock anchor or earthanchor.

Third, the friction on the main surface of the installed pile may beused. When the hydraulic jack is contracted, a force that pulls thefoundation plate downward is generated because the pile is fixed in theground by the main surface friction force.

While the present disclosure has been described with reference to theembodiments shown in the drawings, this is only exemplary, and those ofordinary skill in the art will understand that various modifications andother equivalent embodiments are possible therefrom. Therefore, thescope of the present disclosure should be determined by the technicalspirit of the appended claims.

1. A structure construction method for constructing an undergroundstructure on a ground and sinking the same into the ground, the methodcomprising steps of: A) constructing a foundation plate (10) and a pile(20); B) installing a jack-down device and constructing a basementstructure; C) performing excavation under the foundation plate (10) andsinking the underground structure; and D) dismantling the jack-downdevice and fixing the pile (20), wherein the jack-down device isinstalled on the foundation plate (10), such that a degree of sinking ofthe underground structure is controlled by adjusting force of thejack-down device, wherein the excavation under the foundation plate (10)and the sinking of the underground structure are performed in parallel.2. A structure construction method for constructing an undergroundstructure on a ground and sinking the same into the ground, the methodcomprising steps of: a) constructing an outer foundation plate (50) anda pile (20); b) installing a jack-down device; c) performing excavationunder the outer foundation plate (50) and sinking the undergroundstructure; and d) dismantling the jack-down device and fixing the pile(20), wherein the jack-down device is installed on the outer foundationplate (50), such that a degree of sinking of the underground structureis controlled by adjusting force of the jack-down device, wherein theexcavation under the outer foundation plate (50) and the sinking of theunderground structure are performed in parallel.
 3. The method of claim1 or 2, wherein the sinking is performed by a weight of the undergroundstructure.
 4. The method of claim 1 or 2, wherein the sinking isperformed by a weight of the underground structure and additionalexternal force.
 5. The method for claim 4, wherein the additionalexternal force is generated by: increasing the load by adding atemporary load to the underground structure; using a rock anchor orearth anchor installed in the ground; or using main surface friction ofthe pile installed in the ground.
 6. The method of claim 1 or 2, whereinthe excavation is performed by: using excavation equipment; using awater jet; or suctioning and discharging soil from the ground.
 7. Themethod of claim 1, further comprising: constructing an additionalfoundation plate on the foundation plate (10) and the pile (20) afterthe step D).
 8. The method of claim 2, further comprising: constructingan additional foundation plate on the outer foundation plate (50) andthe pile (20) after the step d).